Venus is one of the only planets in our solar system that doesn't have at least one moon. There are two main theories as to why Venus doesn’t have a moon. One theory holds that the Sun’s gravity simply stole any moon that Venus might have had. The second is the double-impact theory, which posits that a large celestial body hit Venus billions of years ago and created a moon, but several million years later, an even larger celestial object hit Venus, causing the planet’s retrograde rotation and weakening the tidal forces, which ultimately resulted in the moon sinking into Venus and disappearing.